MO dev guide refactoring (#3266) (#3595)

* Release mo dev guide refactoring (#3266)

* Updated MO extension guide

* Minor change and adding svg images

* Added additional information about operation extractors. Fixed links and markdown issues

* Added missing file with information about Caffe Python layers and image for MO transformations dependencies graph

* Added section with common graph transformations attributes and diagram with anchor transformations. Added list of available front phase transformations

* Added description of front-phase transformations except the scope-defined and points defined. Removed legacy document and examples for such transformations.

* Added sections about node name pattern defined front phase transformations. Copy-pasted the old one for the points defined front transformation

* Added description of the rest of front transformations and and all middle and back phase transformations

* Refactored Legacy_Mode_for_Caffe_Custom_Layers and updated the Customize_Model_Optimizer with information about extractors order

* Added TOC for the MO Dev guide document and updated SVG images with PNG ones

* Fixed broken link. Removed redundant image

* Fixed broken links

* Added information about attributes 'run_not_recursively', 'force_clean_up' and 'force_shape_inference' of the transformation

* Code review comments

* Added a section about `Port`s

* Extended Ports description with examples

* Added information about Connections

* Updated MO README.md and removed a lot of redundant and misleading information

* Updates to the Customize_Model_Optimizer.md

* More updates to the Customize_Model_Optimizer.md

* Final updates for the Customize_Model_Optimizer.md

* Fixed some broken links

* More fixed links

* Refactored Custom Layers Guide: removed legacy and incorrect text, added up-to-date.

* Draft implementation of the Custom layer guide example for the MO part

* Fixed broken links using #. Change layer->operation in extensibility documents

* Updated Custom operation guide with IE part

* Fixed broken links and minor updates to the Custom Operations Guide

* Updating links

* Layer->Operation

* Moved FFTOp implementation to the template extension

* Update the CMake for template_extension to build the FFT op conditionally

* Fixed template extension compilation

* Fixed CMake for template extension

* Fixed broken snippet

* Added mri_demo script and updated documentation

* One more compilation error fix

* Added missing header for a demo file

* Added reference to OpenCV

* Fixed unit test for the template extension

* Fixed typos in the template extension

* Fixed compilation of template extension for case when ONNX importer is disabled

Co-authored-by: Alexander Zhogov <alexander.zhogov@intel.com>

docs/MO_DG/Deep_Learning_Model_Optimizer_DevGuide.md

@@ -77,7 +77,6 @@ Model Optimizer produces an Intermediate Representation (IR) of the network, whi
             * [Converting DeepSpeech from TensorFlow](prepare_model/convert_model/tf_specific/Convert_DeepSpeech_From_Tensorflow.md)
             * [Converting Language Model on One Billion Word Benchmark from TensorFlow](prepare_model/convert_model/tf_specific/Convert_lm_1b_From_Tensorflow.md)
             * [Converting Neural Collaborative Filtering Model from TensorFlow*](prepare_model/convert_model/tf_specific/Convert_NCF_From_Tensorflow.md)
-
             * [Converting TensorFlow* Object Detection API Models](prepare_model/convert_model/tf_specific/Convert_Object_Detection_API_Models.md)
             * [Converting TensorFlow*-Slim Image Classification Model Library Models](prepare_model/convert_model/tf_specific/Convert_Slim_Library_Models.md)
             * [Converting CRNN Model from TensorFlow*](prepare_model/convert_model/tf_specific/Convert_CRNN_From_Tensorflow.md)
@@ -91,17 +90,15 @@ Model Optimizer produces an Intermediate Representation (IR) of the network, whi
         * [Model Optimizations Techniques](prepare_model/Model_Optimization_Techniques.md)
         * [Cutting parts of the model](prepare_model/convert_model/Cutting_Model.md)
         * [Sub-graph Replacement in Model Optimizer](prepare_model/customize_model_optimizer/Subgraph_Replacement_Model_Optimizer.md)
-            * [(Deprecated) Case-Study: Converting SSD models created with the TensorFlow* Object Detection API](prepare_model/customize_model_optimizer/TensorFlow_SSD_ObjectDetection_API.md)
-            * [(Deprecated) Case-Study: Converting Faster R-CNN models created with the TensorFlow* Object Detection API](prepare_model/customize_model_optimizer/TensorFlow_Faster_RCNN_ObjectDetection_API.md)
         * [Supported Framework Layers](prepare_model/Supported_Frameworks_Layers.md)
         * [Intermediate Representation and Operation Sets](IR_and_opsets.md)
         * [Operations Specification](../ops/opset.md)
         * [Intermediate Representation suitable for INT8 inference](prepare_model/convert_model/IR_suitable_for_INT8_inference.md)
-
-    * [Custom Layers in Model Optimizer](prepare_model/customize_model_optimizer/Customize_Model_Optimizer.md)
+    * [Model Optimizer Extensibility](prepare_model/customize_model_optimizer/Customize_Model_Optimizer.md)
         * [Extending Model Optimizer with New Primitives](prepare_model/customize_model_optimizer/Extending_Model_Optimizer_with_New_Primitives.md)
+        * [Extending Model Optimizer with Caffe Python Layers](prepare_model/customize_model_optimizer/Extending_Model_Optimizer_with_Caffe_Python_Layers.md)
+        * [Extending Model Optimizer with Custom MXNet* Operations](prepare_model/customize_model_optimizer/Extending_MXNet_Model_Optimizer_with_New_Primitives.md)
         * [Legacy Mode for Caffe* Custom Layers](prepare_model/customize_model_optimizer/Legacy_Mode_for_Caffe_Custom_Layers.md)
-
     * [Model Optimizer Frequently Asked Questions](prepare_model/Model_Optimizer_FAQ.md)
 
 * [Known Issues](Known_Issues_Limitations.md)